| Message ID | 20210217233046.81418-2-vgoyal@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | virtiofsd: Add options to enable/disable posix acl | expand |
On Wed, Feb 17, 2021 at 06:30:44PM -0500, Vivek Goyal wrote: > fuse has an option FUSE_POSIX_ACL which needs to be opted in by fuse > server to enable posix acls. > > Add virtiofsd option "-o posix_acl/no_posix_acl" to let users enable/disable > posix acl support. By default it is disabled as of now. > > Currently even if file server has not opted in for FUSE_POSIX_ACL, user can > still query acl and set acl, and system.posix_acl_access and > system.posix_acl_default xattrs show up listxattr response. > > Miklos said this is confusing. So he said lets block and filter > system.posix_acl_access and system.posix_acl_default xattrs in > getxattr/setxattr/listxattr if user has explicitly disabled > posix acls using -o no_posix_acl. I forgot to block acl xattrs in lo_removexattr(). Will respin this patch. Vivek > > As of now continuing to keeping the existing behavior if user did not > specify any option to disable acl support due to concerns about backward > compatibility. > > v2: block system.posix_acl_access and system.posix_acl_default xattrs > if user explicitly disabled acls. (Miklos) > > Signed-off-by: Vivek Goyal <vgoyal@redhat.com> > --- > tools/virtiofsd/passthrough_ll.c | 95 +++++++++++++++++++++++++++++++- > 1 file changed, 94 insertions(+), 1 deletion(-) > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > index 58d24c0010..26cdfbd1f0 100644 > --- a/tools/virtiofsd/passthrough_ll.c > +++ b/tools/virtiofsd/passthrough_ll.c > @@ -169,6 +169,7 @@ struct lo_data { > /* An O_PATH file descriptor to /proc/self/fd/ */ > int proc_self_fd; > int user_killpriv_v2, killpriv_v2; > + int user_posix_acl; > }; > > static const struct fuse_opt lo_opts[] = { > @@ -201,6 +202,8 @@ static const struct fuse_opt lo_opts[] = { > { "announce_submounts", offsetof(struct lo_data, announce_submounts), 1 }, > { "killpriv_v2", offsetof(struct lo_data, user_killpriv_v2), 1 }, > { "no_killpriv_v2", offsetof(struct lo_data, user_killpriv_v2), 0 }, > + { "posix_acl", offsetof(struct lo_data, user_posix_acl), 1 }, > + { "no_posix_acl", offsetof(struct lo_data, user_posix_acl), 0 }, > FUSE_OPT_END > }; > static bool use_syslog = false; > @@ -661,6 +664,23 @@ static void lo_init(void *userdata, struct fuse_conn_info *conn) > conn->want &= ~FUSE_CAP_HANDLE_KILLPRIV_V2; > lo->killpriv_v2 = 0; > } > + > + if (lo->user_posix_acl == 1) { > + /* > + * User explicitly asked for this option. Enable it unconditionally. > + * If connection does not have this capability, it should fail > + * in fuse_lowlevel.c > + */ > + fuse_log(FUSE_LOG_DEBUG, "lo_init: enabling posix acl\n"); > + conn->want |= FUSE_CAP_POSIX_ACL; > + } else { > + /* > + * Either user specified to disable posix_acl, or did not specify > + * anything. In both the cases do not enable posix acl. > + */ > + fuse_log(FUSE_LOG_DEBUG, "lo_init: disabling posix_acl\n"); > + conn->want &= ~FUSE_CAP_POSIX_ACL; > + } > } > > static void lo_getattr(fuse_req_t req, fuse_ino_t ino, > @@ -2612,6 +2632,63 @@ static int xattr_map_server(const struct lo_data *lo, const char *server_name, > return -ENODATA; > } > > +static bool block_xattr(struct lo_data *lo, const char *name) > +{ > + /* > + * If user explicitly enabled posix_acl or did not provide any option, > + * do not block acl. Otherwise block system.posix_acl_access and > + * system.posix_acl_default xattrs. > + */ > + if (lo->user_posix_acl) { > + return false; > + } > + if (!strcmp(name, "system.posix_acl_access") || > + !strcmp(name, "system.posix_acl_default")) > + return true; > + > + return false; > +} > + > +/* > + * Returns number of bytes in xattr_list after filtering on success. This > + * could be zero as well if nothing is left after filtering. > + * > + * Returns negative error code on failure. > + * xattr_list is modified in place. > + */ > +static int remove_blocked_xattrs(struct lo_data *lo, char *xattr_list, > + unsigned in_size) > +{ > + size_t out_index, in_index; > + > + /* > + * As of now we only filter out acl xattrs. If acls are enabled or > + * they have not been explicitly disabled, there is nothing to > + * filter. > + */ > + if (lo->user_posix_acl) { > + return in_size; > + } > + > + out_index = 0; > + in_index = 0; > + while (in_index < in_size) { > + char *in_ptr = xattr_list + in_index; > + > + /* Length of current attribute name */ > + size_t in_len = strlen(xattr_list + in_index) + 1; > + > + if (!block_xattr(lo, in_ptr)) { > + if (in_index != out_index) { > + memmove(xattr_list + out_index, xattr_list + in_index, in_len); > + } > + out_index += in_len; > + } > + in_index += in_len; > + } > + return out_index; > +} > + > static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name, > size_t size) > { > @@ -2625,6 +2702,11 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name, > int saverr; > int fd = -1; > > + if (block_xattr(lo, in_name)) { > + fuse_reply_err(req, EOPNOTSUPP); > + return; > + } > + > mapped_name = NULL; > name = in_name; > if (lo->xattrmap) { > @@ -2766,7 +2848,6 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) > if (ret == 0) { > goto out; > } > - > if (lo->xattr_map_list) { > /* > * Map the names back, some attributes might be dropped, > @@ -2813,6 +2894,12 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) > goto out; > } > } > + > + ret = remove_blocked_xattrs(lo, value, ret); > + if (ret <= 0) { > + saverr = -ret; > + goto out; > + } > fuse_reply_buf(req, value, ret); > } else { > /* > @@ -2851,6 +2938,11 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name, > int saverr; > int fd = -1; > > + if (block_xattr(lo, in_name)) { > + fuse_reply_err(req, EOPNOTSUPP); > + return; > + } > + > mapped_name = NULL; > name = in_name; > if (lo->xattrmap) { > @@ -3604,6 +3696,7 @@ int main(int argc, char *argv[]) > .allow_direct_io = 0, > .proc_self_fd = -1, > .user_killpriv_v2 = -1, > + .user_posix_acl = -1, > }; > struct lo_map_elem *root_elem; > struct lo_map_elem *reserve_elem; > -- > 2.25.4 >
fuse has an option FUSE_POSIX_ACL which needs to be opted in by fuse
server to enable posix acls.
Add virtiofsd option "-o posix_acl/no_posix_acl" to let users enable/disable
posix acl support. By default it is disabled as of now.
Currently even if file server has not opted in for FUSE_POSIX_ACL, user can
still query acl and set acl, and system.posix_acl_access and
system.posix_acl_default xattrs show up listxattr response.
Miklos said this is confusing. So he said lets block and filter
system.posix_acl_access and system.posix_acl_default xattrs in
getxattr/setxattr/listxattr if user has explicitly disabled
posix acls using -o no_posix_acl.
As of now continuing to keeping the existing behavior if user did not
specify any option to disable acl support due to concerns about backward
compatibility.
v2.1: Fixed lo_removexattr()
v2: block system.posix_acl_access and system.posix_acl_default xattrs
if user explicitly disabled acls. (Miklos)
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
tools/virtiofsd/passthrough_ll.c | 100 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 99 insertions(+), 1 deletion(-)
Index: rhvgoyal-qemu/tools/virtiofsd/passthrough_ll.c
===================================================================
--- rhvgoyal-qemu.orig/tools/virtiofsd/passthrough_ll.c 2021-02-18 13:12:26.839770339 -0500
+++ rhvgoyal-qemu/tools/virtiofsd/passthrough_ll.c 2021-02-18 13:38:22.344930118 -0500
@@ -169,6 +169,7 @@ struct lo_data {
/* An O_PATH file descriptor to /proc/self/fd/ */
int proc_self_fd;
int user_killpriv_v2, killpriv_v2;
+ int user_posix_acl;
};
static const struct fuse_opt lo_opts[] = {
@@ -201,6 +202,8 @@ static const struct fuse_opt lo_opts[] =
{ "announce_submounts", offsetof(struct lo_data, announce_submounts), 1 },
{ "killpriv_v2", offsetof(struct lo_data, user_killpriv_v2), 1 },
{ "no_killpriv_v2", offsetof(struct lo_data, user_killpriv_v2), 0 },
+ { "posix_acl", offsetof(struct lo_data, user_posix_acl), 1 },
+ { "no_posix_acl", offsetof(struct lo_data, user_posix_acl), 0 },
FUSE_OPT_END
};
static bool use_syslog = false;
@@ -661,6 +664,23 @@ static void lo_init(void *userdata, stru
conn->want &= ~FUSE_CAP_HANDLE_KILLPRIV_V2;
lo->killpriv_v2 = 0;
}
+
+ if (lo->user_posix_acl == 1) {
+ /*
+ * User explicitly asked for this option. Enable it unconditionally.
+ * If connection does not have this capability, it should fail
+ * in fuse_lowlevel.c
+ */
+ fuse_log(FUSE_LOG_DEBUG, "lo_init: enabling posix acl\n");
+ conn->want |= FUSE_CAP_POSIX_ACL;
+ } else {
+ /*
+ * Either user specified to disable posix_acl, or did not specify
+ * anything. In both the cases do not enable posix acl.
+ */
+ fuse_log(FUSE_LOG_DEBUG, "lo_init: disabling posix_acl\n");
+ conn->want &= ~FUSE_CAP_POSIX_ACL;
+ }
}
static void lo_getattr(fuse_req_t req, fuse_ino_t ino,
@@ -2612,6 +2632,63 @@ static int xattr_map_server(const struct
return -ENODATA;
}
+static bool block_xattr(struct lo_data *lo, const char *name)
+{
+ /*
+ * If user explicitly enabled posix_acl or did not provide any option,
+ * do not block acl. Otherwise block system.posix_acl_access and
+ * system.posix_acl_default xattrs.
+ */
+ if (lo->user_posix_acl) {
+ return false;
+ }
+ if (!strcmp(name, "system.posix_acl_access") ||
+ !strcmp(name, "system.posix_acl_default"))
+ return true;
+
+ return false;
+}
+
+/*
+ * Returns number of bytes in xattr_list after filtering on success. This
+ * could be zero as well if nothing is left after filtering.
+ *
+ * Returns negative error code on failure.
+ * xattr_list is modified in place.
+ */
+static int remove_blocked_xattrs(struct lo_data *lo, char *xattr_list,
+ unsigned in_size)
+{
+ size_t out_index, in_index;
+
+ /*
+ * As of now we only filter out acl xattrs. If acls are enabled or
+ * they have not been explicitly disabled, there is nothing to
+ * filter.
+ */
+ if (lo->user_posix_acl) {
+ return in_size;
+ }
+
+ out_index = 0;
+ in_index = 0;
+ while (in_index < in_size) {
+ char *in_ptr = xattr_list + in_index;
+
+ /* Length of current attribute name */
+ size_t in_len = strlen(xattr_list + in_index) + 1;
+
+ if (!block_xattr(lo, in_ptr)) {
+ if (in_index != out_index) {
+ memmove(xattr_list + out_index, xattr_list + in_index, in_len);
+ }
+ out_index += in_len;
+ }
+ in_index += in_len;
+ }
+ return out_index;
+}
+
static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name,
size_t size)
{
@@ -2625,6 +2702,11 @@ static void lo_getxattr(fuse_req_t req,
int saverr;
int fd = -1;
+ if (block_xattr(lo, in_name)) {
+ fuse_reply_err(req, EOPNOTSUPP);
+ return;
+ }
+
mapped_name = NULL;
name = in_name;
if (lo->xattrmap) {
@@ -2766,7 +2848,6 @@ static void lo_listxattr(fuse_req_t req,
if (ret == 0) {
goto out;
}
-
if (lo->xattr_map_list) {
/*
* Map the names back, some attributes might be dropped,
@@ -2813,6 +2894,12 @@ static void lo_listxattr(fuse_req_t req,
goto out;
}
}
+
+ ret = remove_blocked_xattrs(lo, value, ret);
+ if (ret <= 0) {
+ saverr = -ret;
+ goto out;
+ }
fuse_reply_buf(req, value, ret);
} else {
/*
@@ -2851,6 +2938,11 @@ static void lo_setxattr(fuse_req_t req,
int saverr;
int fd = -1;
+ if (block_xattr(lo, in_name)) {
+ fuse_reply_err(req, EOPNOTSUPP);
+ return;
+ }
+
mapped_name = NULL;
name = in_name;
if (lo->xattrmap) {
@@ -2917,6 +3009,11 @@ static void lo_removexattr(fuse_req_t re
int saverr;
int fd = -1;
+ if (block_xattr(lo, in_name)) {
+ fuse_reply_err(req, EOPNOTSUPP);
+ return;
+ }
+
mapped_name = NULL;
name = in_name;
if (lo->xattrmap) {
@@ -3604,6 +3701,7 @@ int main(int argc, char *argv[])
.allow_direct_io = 0,
.proc_self_fd = -1,
.user_killpriv_v2 = -1,
+ .user_posix_acl = -1,
};
struct lo_map_elem *root_elem;
struct lo_map_elem *reserve_elem;
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index 58d24c0010..26cdfbd1f0 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -169,6 +169,7 @@ struct lo_data { /* An O_PATH file descriptor to /proc/self/fd/ */ int proc_self_fd; int user_killpriv_v2, killpriv_v2; + int user_posix_acl; }; static const struct fuse_opt lo_opts[] = { @@ -201,6 +202,8 @@ static const struct fuse_opt lo_opts[] = { { "announce_submounts", offsetof(struct lo_data, announce_submounts), 1 }, { "killpriv_v2", offsetof(struct lo_data, user_killpriv_v2), 1 }, { "no_killpriv_v2", offsetof(struct lo_data, user_killpriv_v2), 0 }, + { "posix_acl", offsetof(struct lo_data, user_posix_acl), 1 }, + { "no_posix_acl", offsetof(struct lo_data, user_posix_acl), 0 }, FUSE_OPT_END }; static bool use_syslog = false; @@ -661,6 +664,23 @@ static void lo_init(void *userdata, struct fuse_conn_info *conn) conn->want &= ~FUSE_CAP_HANDLE_KILLPRIV_V2; lo->killpriv_v2 = 0; } + + if (lo->user_posix_acl == 1) { + /* + * User explicitly asked for this option. Enable it unconditionally. + * If connection does not have this capability, it should fail + * in fuse_lowlevel.c + */ + fuse_log(FUSE_LOG_DEBUG, "lo_init: enabling posix acl\n"); + conn->want |= FUSE_CAP_POSIX_ACL; + } else { + /* + * Either user specified to disable posix_acl, or did not specify + * anything. In both the cases do not enable posix acl. + */ + fuse_log(FUSE_LOG_DEBUG, "lo_init: disabling posix_acl\n"); + conn->want &= ~FUSE_CAP_POSIX_ACL; + } } static void lo_getattr(fuse_req_t req, fuse_ino_t ino, @@ -2612,6 +2632,63 @@ static int xattr_map_server(const struct lo_data *lo, const char *server_name, return -ENODATA; } +static bool block_xattr(struct lo_data *lo, const char *name) +{ + /* + * If user explicitly enabled posix_acl or did not provide any option, + * do not block acl. Otherwise block system.posix_acl_access and + * system.posix_acl_default xattrs. + */ + if (lo->user_posix_acl) { + return false; + } + if (!strcmp(name, "system.posix_acl_access") || + !strcmp(name, "system.posix_acl_default")) + return true; + + return false; +} + +/* + * Returns number of bytes in xattr_list after filtering on success. This + * could be zero as well if nothing is left after filtering. + * + * Returns negative error code on failure. + * xattr_list is modified in place. + */ +static int remove_blocked_xattrs(struct lo_data *lo, char *xattr_list, + unsigned in_size) +{ + size_t out_index, in_index; + + /* + * As of now we only filter out acl xattrs. If acls are enabled or + * they have not been explicitly disabled, there is nothing to + * filter. + */ + if (lo->user_posix_acl) { + return in_size; + } + + out_index = 0; + in_index = 0; + while (in_index < in_size) { + char *in_ptr = xattr_list + in_index; + + /* Length of current attribute name */ + size_t in_len = strlen(xattr_list + in_index) + 1; + + if (!block_xattr(lo, in_ptr)) { + if (in_index != out_index) { + memmove(xattr_list + out_index, xattr_list + in_index, in_len); + } + out_index += in_len; + } + in_index += in_len; + } + return out_index; +} + static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name, size_t size) { @@ -2625,6 +2702,11 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name, int saverr; int fd = -1; + if (block_xattr(lo, in_name)) { + fuse_reply_err(req, EOPNOTSUPP); + return; + } + mapped_name = NULL; name = in_name; if (lo->xattrmap) { @@ -2766,7 +2848,6 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) if (ret == 0) { goto out; } - if (lo->xattr_map_list) { /* * Map the names back, some attributes might be dropped, @@ -2813,6 +2894,12 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) goto out; } } + + ret = remove_blocked_xattrs(lo, value, ret); + if (ret <= 0) { + saverr = -ret; + goto out; + } fuse_reply_buf(req, value, ret); } else { /* @@ -2851,6 +2938,11 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name, int saverr; int fd = -1; + if (block_xattr(lo, in_name)) { + fuse_reply_err(req, EOPNOTSUPP); + return; + } + mapped_name = NULL; name = in_name; if (lo->xattrmap) { @@ -3604,6 +3696,7 @@ int main(int argc, char *argv[]) .allow_direct_io = 0, .proc_self_fd = -1, .user_killpriv_v2 = -1, + .user_posix_acl = -1, }; struct lo_map_elem *root_elem; struct lo_map_elem *reserve_elem;
fuse has an option FUSE_POSIX_ACL which needs to be opted in by fuse server to enable posix acls. Add virtiofsd option "-o posix_acl/no_posix_acl" to let users enable/disable posix acl support. By default it is disabled as of now. Currently even if file server has not opted in for FUSE_POSIX_ACL, user can still query acl and set acl, and system.posix_acl_access and system.posix_acl_default xattrs show up listxattr response. Miklos said this is confusing. So he said lets block and filter system.posix_acl_access and system.posix_acl_default xattrs in getxattr/setxattr/listxattr if user has explicitly disabled posix acls using -o no_posix_acl. As of now continuing to keeping the existing behavior if user did not specify any option to disable acl support due to concerns about backward compatibility. v2: block system.posix_acl_access and system.posix_acl_default xattrs if user explicitly disabled acls. (Miklos) Signed-off-by: Vivek Goyal <vgoyal@redhat.com> --- tools/virtiofsd/passthrough_ll.c | 95 +++++++++++++++++++++++++++++++- 1 file changed, 94 insertions(+), 1 deletion(-)